This invention generally relates to a storage apparatus for receiving and storing nuclear waste for safe handling and transportation to a disposal site. More specifically, the present invention relates to a multi-layer nuclear waste storage container including a self-sealing layer of material that can be penetrated for safe and efficient filling of the container during the filling process.
Prior art apparatus and systems for nuclear waste storage typically have a concrete construction. A typical nuclear waste storage container is formed as a pre-cast modular concrete container. Concrete has been found to be a durable material for storage containers containing certain levels of radiation and certain forms of radioactive waste. For further protection against leakage, concrete containers have been provided with various lining materials. For example, granular fill material or grout has been poured into concrete containers to secure waste packages in place and to provide an additional barrier to radiation leakage. This type of lining material has been found to be effective for low level and short-lived radioactive wastes. This type of lining is described in U.S. Pat. No. 4,950,426.
Depending on the half-life of the particular radioactive material being handled, radioactive waste can remain as a hazardous material for 200 years or more. Such instances require a liner that is sufficiently durable over a long period while providing a leak-tight barrier for the radioactive waste. These types of liners are typically installed within a pre-formed concrete container. An impermeable liner disposed within a pre-cast concrete container is described in U.S. Pat. No. 5,431,295. The liner is a one-piece plastic molded liner that is inserted into the concrete container mold before the concrete is poured. The liner has ribs that are embedded into the concrete.
The use of concrete as a material for a storage container has some disadvantages. While providing a durable construction, concrete is not highly elastic and may chip or be damaged when subject to high impact, especially during transportation. Furthermore, these concrete containers utilize storage lids that do not provide a closed environment during the container filling process. The container lid must be removed while the container is filled.
Thus, there is a need for a nuclear waste storage container construction that eliminates the use of concrete and that is capable of being filled in a substantially sealed configuration. Furthermore, there is a need for a nuclear waste storage container construction that utilizes an outer material that has sufficient elastic properties while maintaining durability.
The present invention is a nuclear waste storage apparatus and a method of filling the storage apparatus while the storage apparatus remains substantially sealed. The apparatus is a container that can take the form of several different shapes and its construction comprises several layers. The innermost layer of the container comprises a rubber or plastic material that is self-sealing. The inner layer acts as a bladder for the contents of the container. This bladder is covered by a second layer of protective coating material. A radiation barrier layer is disposed over the protective coating layer. An outer layer of an elastic impact resistant material is disposed over the radiation barrier layer to complete the container construction.
Prior to coating the inner bladder with the subsequent layers, the inner bladder is filled with radioactive waste material prepared in slurry form. An injection device pierces the bladder and fills it in a substantially sealed process. When the injector is removed, the self-sealing material of the inner bladder substantially closes the pierced portion of the bladder. The bladder is then coated with the protective coating, the radioactive barrier coating, and the outer impact resistant coating.